1. Field of the Invention
The present invention relates to an automotive air conditioner having a plate-like mixing door for controlling flows of cold and hot air by slide-moving the mixing door within a unit casing, and more particularly to an automotive air conditioner for reducing the spraying of condensate or condensed water produced in an evaporator.
The present application is based on Japanese Patent Application No. Hei. 11-236122, which is incorporated herein by reference.
2. Description of the Related Art
In a conventional automotive air conditioner, inside and outside air is selectively taken in by means of an intake unit and is then led into a cooling unit casing (hereinafter, simply referred to as a unit casing). The air is then passed through an evaporator in the unit casing so as to be cooled. This cooled air is thereafter heated by means of a heater core or is caused to bypass the heater core so as to be mixed with the heated air for production of conditioned air of a predetermined temperature, the conditioned air then being discharged into the passenger compartment from various types of outlets. Here, the xe2x80x9cevaporatorxe2x80x9d is a known device for allowing a low-temperature and low-pressure refrigerant which is reduced in pressure by means of an expansion valve provided in a refrigeration cycle to flow throughout it for heat exchange with air passing through it to thereby cool the refrigerant. In addition, the xe2x80x9cheater corexe2x80x9d is a device for allowing hot engine coolant to flow through the inside thereof for heat exchange with air passing through it to thereby heat the air.
With the automotive air conditioner constructed as described above, since the air conditioner is placed in a narrow passenger compartment of a vehicle, there is a limitation to the overall dimensions thereof in view of a constraint with respect to space inside the passenger compartment. To cope with this, in recent years, a so-called integral type becomes known in which an evaporator and a heater core are accommodated within a single unit casing in such a manner that they are disposed relatively vertically with each being disposed substantially horizontally.
Furthermore, a mixing door is interposed between the evaporator and the heater core for causing cooled air to branch at a predetermined ratio into one passage where cooled air is allowed to pass through the heater core and the other passage where cooled air is caused to bypass the heater core. If the mixing door is constructed so as to supported on one fulcrum to thereby rotate about the fulcrum, the mixing door becomes large and hence occupies a large space inside the passenger compartment. To make shorter the distance between the evaporator and the heater core so as to avoid this, it is conceived to design the mixing door as a flat plate-like door which slidably moves.
FIG. 7 is a schematic sectional view of an integral-type automotive air conditioner having a plate-like mixing door which slidably moves and in which an evaporator and a heater core are disposed substantially horizontally within a unit casing.
In the integral-type automotive air conditioner shown in FIG. 7, the evaporator 2 is disposed at a lower portion of the unit casing 1 in such a manner that the air passing plane is inclined, and the heater core 4 is provided above the evaporator 2. The plate-like mixing door 50 is provided between the evaporator 2 and the heater core 4 in such a manner that the mixing door which slidably moves in a substantially horizontal direction. This mixing door 50 causes air (cold air) that has passed through the evaporator 2 to branch at a predetermined ratio into a hot air passage 3 side where air is allowed to pass through the heater core 4 and a bypass passage 6 side where air is allowed to bypass the heater core 4. And cold air that has passed through the bypass passage 6 from the evaporator 2 and hot air that has passed through the hot air passage 3 from the heater core 4 and been guided by a partition wall 7 are mixed with each other in a mixing zone 8, whereby a conditioned air of the desired temperature is produced.
In a ventilating mode (refrigerating mode), cold air is discharged from a vent Ov adapted to be closed by a vent door Dv provided at an upper portion in the unit casing 1. In a defogging or defrosting mode (mode for clearing fogging or frosting of the window glass), air (mainly hot air) flowing from a def-foot outlet Odf which is now opened by moving the vent door DV into an upper passage 9 formed by the partition wall 7 and the unit casing 1 is discharged from a defroster outlet Od which is closed by a def-foot door Ddf. In a foot mode (heating mode) in which conditioned air is discharged toward the feet of the driver and other passengers in the passenger compartment, air (mainly hot air) flowing from the def-foot outlet Odf into the upper passage 9 is discharged from a foot outlet Of which is closed by the def-foot door Ddf.
In the integral-type automotive air conditioner shown in FIG. 7, however, especially when the refrigeration system is in full operation, air passing through the evaporator 2 and flowing toward the mixing door 50 in a direction indicated by an arrow A0 shown in the figure is guided along the surface of the mixing door 50 and flows in a direction indicated by an arrow A0xe2x80x2 shown in the same figure. This narrows a flow of air (air axis) F0 flowing into the cold air passage 6, and as a result of this, there is caused a problem that the air flow velocity becomes too fast.
As a result of this, there is caused a problem that condensed water in the air resulting from a heat exchange at the evaporator 2 is easily sprayed from the vent Ov by the air flow of too fast velocity in the upward direction.
To cope with this, an object of the present invention is to provide an automotive air conditioner comprising a slidingly movable plate-like mixing door which can reduce the spraying of condensed water produced at the evaporator while reducing the size of the air conditioner.
The object of the invention is to be accomplished by a means that will be described below.
According to a first feature of the invention, there is provided an automotive air conditioner comprising a plate-like mixing door provided between an evaporator and a heater core disposed within a unit casing, so that air passing through the evaporator is caused to branch at a predetermined ratio into a hot air passage side where the air is allowed to pass through the heater core and a bypass passage side where the air is caused to bypass the heater core by slide moving the mixing door for mixing in a mixing zone cold air sent through the bypass passage and hot air sent through the hot air passage and thereafter allowing an air so mixed or conditioned to be discharged into a passenger compartment through outlets (Ov, Of, Od) formed in the unit casing, the automotive air conditioner being characterized in that the surface of the mixing door is curved convexly toward an upstream side of an air flow in the vicinity of a central portion thereof where the air flow is brought into direct contact therewith.
According to a second feature of the invention, there is provided an automotive air conditioner as set forth in the first feature of the invention above, wherein the evaporator and the heater core are disposed substantially horizontally, respectively, below the unit casing and above the evaporator.
According to a third feature of the invention, there is provided an automotive air conditioner as set forth in the first feature of the invention above, wherein the evaporator and the heater core are, respectively, disposed substantially vertically.
According to a fourth feature of the invention, there is provided an automotive air conditioner as set forth in the first feature of the invention above, wherein hot air sent through the hot air passage is caused to flow along a back of the mixing door which is curved concavely.
According to a fifth feature of the invention, there is provided an automotive air conditioner as set forth in the fourth feature of the invention above, having a foot door for guiding hot air sent from the hot air passage into the mixing zone in cooperation with the concavely curved back of the mixing door.
According to a sixth feature of the invention, there is provided an automotive air conditioner as set forth in either the first or second feature of the invention above, wherein the mixing door has racks adapted to be brought into mesh engagement with rotatable gears provided on an upstream side of the mixing door, and wherein the racks are curved concavely toward the downstream side of the air flow.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.